Computer Repair · October 23, 2026 · ComputerKing Team

How to Choose a NAS for Home or a Small Office

Buying a NAS goes wrong most often in three places: the wrong drive, the wrong array, and a skipped first-day setup. This guide starts from what you will actually use it for, compares new models, drives, backup and remote access, and ends with a setup checklist so you can get the decision right the first time.

Key summary

Buying a NAS goes wrong most often in three places: the wrong drive, the wrong array, and a skipped first-day setup. This guide starts from what you will actually use it for, compares new models, drives, backup and remote access, and ends with a setup checklist so you can get the decision right the first time.

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Brief recap: what our earlier guide already covers

Our introductory guide to home and small-office NAS already covers the basics: what a NAS is, how to size capacity and bays, RAID fundamentals, landing the 3-2-1 backup rule and three remote-access methods. This article does not repeat that material; it focuses on the pre-purchase decision: 2025–2026 model comparisons, CMR drive selection, array expansion paths, Hong Kong broadband and LAN bottlenecks, three-layer backup, remote-access security, multi-user permissions, UPS power protection and a first-day checklist.

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Before buying, answer four questions

Most people start by asking, "How many bays do I need?" Bay count is actually the last question to answer. Start with these four, because the answers decide the bay count, the brand ecosystem, whether you need a UPS, and how backup should work.

First, is this NAS your "only copy" or "one of several copies"? If every photo, document and account record at home or in the office lives only on this NAS, that is not good enough. A sound backup needs at least three copies, on two different media, with one copy offsite. An array on its own is not a backup, as explained below.

Second, who needs to open files from outside the home or office? Occasionally looking at photos from outside and a whole team working remotely every day need completely different remote-access solutions. Convenience and exposed attack surface are a trade-off; you cannot have maximum convenience and zero risk at the same time.

Third, how many people share it? One person and ten people need very different setups. Once several people share a NAS, you need group permissions, quotas, versioning and a recycle bin. Never let a whole company share one administrator account.

Fourth, what happens in a power cut? A UPS with no signal cable is just a big battery. The NAS has no idea the power is out, and when the battery runs flat the result is still a hard power cut. Only a UPS plus a signal cable plus automatic safe shutdown counts as a finished setup.

Only after answering those four should you compare models. This guide follows the order of a buying decision: new models, drives, arrays, Hong Kong broadband and the local network, three-layer backup, remote-access security, multi-user setup, power-cut protection, and finally a first-day checklist.

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1. New models in 2025–2026: look at the use case first, then the bay count

Synology: the 2025 Plus range is still the main line, with a cheaper line added in 2026

The Synology 2025 Plus range shares 2.5GbE ports; M.2 slots are included except on the entry model, the DS225+. The differences are mainly bay count, processor, memory and expansion. Note that the cheapest model in the 2025 range with an official 10GbE upgrade path is the 5-bay model; the 2-bay and 4-bay mainstream models have more limited upgrade paths, so check before buying whether you will need a faster local network within three years.

The cheaper line launched in 2026 (DS725neo+, DS925neo+, DS1525neo+, DS1825neo+) keeps roughly the same processor, bay count, network ports, M.2 slots and expansion as the same-name Plus version. The only hardware difference is memory: the 2-bay and 4-bay versions keep the same capacity but change from ECC to non-ECC; the 5-bay and 8-bay versions drop from 8 GB ECC to 4 GB non-ECC. The maximum is still 32 GB, but switching back to ECC later means replacing the whole memory module — ECC and non-ECC cannot be mixed. DS425+ / DS225+ are not part of the neo+ line; their memory specifications (DS425+ up to 6 GB) differ from the neo+ line (up to 32 GB), so do not confuse the two. For buyers who care about data integrity, that matters, so think before choosing the cheaper line.

One point needs special care: the standard memory capacity of the entry 2-bay model is in conflict between two secondary round-ups, one saying 4 GB and the other saying 2 GB on board with a 6 GB maximum. This article does not settle the question; buyers should check the official Synology specification page for that model directly, and not trust a retailer page or a secondary round-up.

Also note that these Synology V1500B models have no built-in GPU, so there is no hardware transcoding; media transcoding relies on software. If you often need on-the-fly transcoding for video, factor that in.

On price: US market reference prices found during research are US references only. No public source for Hong Kong authorised prices was found, so this article states "no public source, please request an individual quotation" and never presents a US dollar price as a Hong Kong price.

QNAP: the current main line is still the previous generation; most 2026 newcomers are only shown, not on sale

QNAP's current mainstream models are still the TS-x64 and TS-x73A generations. The entry 2-bay model uses an ARM processor and 2 GB of memory, and memory is the bottleneck — it is not suitable for containers, virtual machines or heavy transcoding. The 2-bay model with more headroom uses an Intel processor, 8 GB of memory and dual 2.5GbE, but a 2-bay mirror gives only half the capacity as usable space, and you cannot add a third drive later. That limit must be known before buying.

For 4-bay models, both the Intel and the AMD Ryzen V1500B models are mainstream choices for home and small offices, with the latter offering more memory expansion room. There is also a short-depth rackmount 4-bay model for small cabinets and wall-mount racks. It is a rackmount unit, not a desktop home unit, and home buyers should not buy it as a desktop NAS.

The new 2-bay and 4-bay models shown at exhibitions in 2026 use an Intel N150 processor, support DDR5 and dual 2.5GbE, and can be upgraded to 10GbE through a PCIe slot. However, price and launch date have not been announced, so this article describes them only as "shown, not yet on sale" and does not recommend them as current models. Buyers waiting for them should expect no confirmed launch date yet.

UGREEN and Asustor: the most aggressive network ports, but check the positioning

UGREEN's NASync lines are clearly separated, and its network ports are the most aggressive of the four brands. The entry 2-bay model (DXP2800) uses an Intel N100 processor, 8 GB DDR5 and 2.5GbE; the mainstream 4-bay model (DXP4800) has dual 2.5GbE that can be aggregated to 5G; the advanced 4-bay model (DXP4800 Plus) already has 10GbE plus 2.5GbE. The 2026 new line (DXP2800 GT / DXP4800 GT) uses an AMD Ryzen processor with built-in graphics, so hardware transcoding is a difference from Synology's V1500B models; the 2-bay version has one 10GbE port and the 4-bay version has two. Note, however, that the new line's 2-bay version only supports mirroring, and only the 4-bay version offers RAID 5, 6 and 10. The 6-bay high-end model (DXP6800 Pro) uses an Intel Core i5 processor, dual 10GbE plus dual Thunderbolt, and is a creator / high-end choice, not a general home entry model.

Asustor's Lockerstor Gen2+ v2 line, launched in late 2025, uses an Intel Celeron N5105 processor across the board, dual 5GbE ports (which can be combined to 10 Gbps with SMB multichannel) and four M.2 slots. The 2-bay and 4-bay models ship with 4 GB and the 6-bay model with 8 GB, up to 16 GB. However, the N5105 is a chip from 2021, and multiple sources agree its performance is only enough for general files, backup and light containers; heavy Docker, virtual machines or surveillance use needs careful thought. Also, Asustor expansion units are independent storage pools, unlike Synology, where the original volume can span the main unit and the expansion unit. Know that before buying an expansion unit.

US market reference prices exist for UGREEN and Asustor in secondary round-ups, but Hong Kong prices likewise have no public source and must be quoted individually. This article does not present US prices as Hong Kong prices.

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2. Choosing drives: for an array, buy CMR, and do not judge by the series name alone

Further reading: Clicking Hard Drive? Power Off Now: 2026 Recovery & Myth Guide (HK)

NAS drives differ from ordinary desktop drives in three real ways. First, NAS drives are designed for continuous operation and multi-drive vibration environments; a desktop drive's power-saving and spin-down behaviour can become a disadvantage inside an array. Second, NAS drives have rotation vibration sensors: when several drives spin together they vibrate each other, and the sensor detects this and adjusts the head, reducing latency and errors. This matters most with three or four or more drives in one enclosure. Third, limited error recovery time: an ordinary drive that cannot read will keep retrying for a long time, and the array may wrongly conclude it is dead and kick it out; a NAS drive gives up within a time limit so the array can handle the problem with mirroring or parity.

More important still is CMR versus SMR. The one-line rule is: for an array, buy CMR. In CMR (conventional magnetic recording), tracks sit side by side without overlapping, so random writes and rewrites stay stable. In SMR (shingled magnetic recording), tracks overlap like roof tiles, giving about 25% higher density at a lower price, but rewriting one track may require rewriting neighbouring tracks as well. Ordinary sequential writes may not show the problem, but an array rebuild — a sustained heavy-write workload — can slow down for days and even cause the new drive to be kicked out of the array.

On the safe list, Seagate IronWolf and IronWolf Pro, WD Red Plus and WD Red Pro, and Toshiba N300 and N300 Pro are CMR. On the avoid list for arrays, the plain WD Red (EFAX, 2–6 TB) is SMR; WD Blue 3.5-inch, Seagate BarraCuda 3.5-inch 4 TB and 8 TB, and Toshiba P300 4 TB and 6 TB are mixed or SMR, so check the exact model number before buying and do not rely on the series name alone. WD's naming trap still catches buyers today: plain WD Red is SMR, WD Red Plus is CMR, and WD Red Pro is CMR. One word of difference, very different result.

One more point buyers must know: the compatibility-list policy has changed. In early 2025, Synology's 2025 Plus models initially required approved drives before a new storage pool could be created. On 7–8 October 2025, DSM 7.3 relaxed this: 2025 Plus, Value and J series models running DSM 7.3 support installing and creating a new storage pool with unverified third-party 3.5-inch hard drives and 2.5-inch SATA solid-state drives. But M.2 solid-state drives used to create a pool or as cache still need to be on the compatibility list. The cheaper line launched in 2026 had no such out-of-box restriction, and third-party hard drives work out of the box. The practical conclusion is simple: for a 2025 Plus model, confirm the system version is 7.3 or above; before buying an M.2 drive for a pool or cache, check that model's compatibility list first, and do not assume any M.2 drive will work.

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3. Array comparison: bay count decides whether you still have a road ahead

Further reading: Hong Kong SME RAID Recovery: What to Do When It Fails

In the formulas below, N is the number of drives and S is the capacity of the smallest drive; traditional arrays always use the smallest drive as the reference.

Three expansion warnings are worth remembering. First, the moment you buy a 2-bay unit, you give up the future path of "adding a third drive to convert to RAID 5 or 6"; changing later means moving the whole data set or replacing the unit. Second, before any array conversion, drive replacement or rebuild, make an independent backup first; during a rebuild, do not pull out other drives and do not rush it — wait for the rebuild to finish. Third, use drives of the same capacity in one array where possible, and label each physical drive against its bay number so that when the NAS reports a failed drive, you replace the right one.

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4. Hong Kong context: the remote-access bottleneck is upload speed; the local-network bottleneck is the slowest link

Many people assume that a fast NAS network port means fast file access from outside. They are two different things. The local network speed between a NAS and a computer at home, and the home broadband upload speed to the outside world, are completely different concepts. Even with 2.5G or 10G at home, the speed of downloading files when you are out is still capped by the home broadband upload limit.

For Hong Kong measured background, according to Ookla's first-half 2026 report, Netvigator home broadband was Hong Kong's fastest fixed ISP, with median download of 482.31 Mbps and median upload of 379.94 Mbps. To be clear: it is the median across all plans in Hong Kong, not a guaranteed speed for any individual plan. Individual users should rely on their own plan and their own test results, and must not treat the median as a guarantee.

As a plan specification example, NETVIGATOR's 2 x 1000M multi-use service states maximum download of 2000 Mbps and maximum upload of 1000 Mbps, made up of two 1000 Mbps fibre ports each, and states plainly that actual speeds will be below the network specification, affected by equipment, technology, network settings, usage, international bandwidth and other factors. Another provider's speed guarantee terms also require the test computer to be connected directly to the wall socket or fibre terminal, without a third-party router; 2000M or 2.5G plans further require the computer itself to have a 2.5G port before the speed can even be measured. In other words, "the plan says 2500M" does not mean you get 2500M through an ordinary router and Wi-Fi.

Before buying a NAS, test your home upload speed once with a wired direct connection. If upload is only a few tens of Mbps, watching 4K original footage remotely or syncing a whole photo library will stutter, and changing the NAS will not fix it.

For local network upgrades, the most important principle is the "slowest link". If any link in the chain between the NAS and the computer (router, switch, cable, computer network card, NAS network card) is only 100 Mbps, the whole chain runs at 12.5 MB/s; the advertised speed is only reached when the whole chain runs at the same speed. Cable requirements are more forgiving than people expect: for 2.5G, Cat5e is enough within 100 metres, and there is no need to rewire the whole home; 5G needs Cat6 and 10G calls for Cat6A. New cables can be bought as Cat6 directly to leave room for 5G, but an old Cat5e cable with intact connectors and no damage can generally run 2.5G.

A sensible upgrade order is: first confirm whether the ISP handover and router can really use more than 1G, then add a small 2.5G switch where fast devices are concentrated, then upgrade one by one the devices that actually move large files (main computer, NAS, Wi-Fi access point), then replace weak patch cables and check the actual negotiated speed. Ordinary devices can stay on 1G. Also note that a single mechanical hard drive may not even fill a 2.5G link on its own; the value of 2.5G or 10G lies mainly in solid-state cache, several people accessing at once, or editing video directly on the NAS. Do not oversell 10G benefits to a home buyer who only does backup. Use wired connections for large transfers where possible, as Wi-Fi fluctuates; when only Wi-Fi is possible, 5 GHz at close range is more stable.

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5. Three-layer backup: an array is not a backup, and a snapshot is not an offsite backup

Further reading: Hong Kong Backup Strategy Guide: The 3-2-1 Rule Done Properly — Time Machine, Windows, Cloud and Offline Drives

This is the most important "making it real" section of the article. An array only protects against one (or two) failed drives so the service keeps running. It does not protect against mistaken deletion, overwriting, ransomware encryption, file corruption, fire, flooding, theft, or the whole NAS failing. A deleted or encrypted file is immediately reflected to the mirror or parity side, and the array cannot recover it. The correct approach is that, beyond the array, important data needs at least one more copy separate from the NAS, and it only counts once a restore has been tested.

Snapshots and backups are different things. A snapshot is an instant status record within the same unit and the same storage pool, used to quickly restore a mistakenly deleted or wrongly changed file. Its advantages are speed and small space use. But the snapshot itself still sits on the same NAS: if the unit is stolen, damaged by fire or flooding, or the whole storage pool is corrupted, the snapshot goes with it. A backup is what copies data to another medium or another location.

Synology's official backup strategy defines the rule as three copies, two different media, one offsite, and notes that hardware or software failure, data corruption, ransomware or accidental deletion are all scenarios backup must guard against. QNAP's official guide uses the same wording — three copies, two media, one offsite — and names Hybrid Backup Sync (HBS) as the native solution, able to back up to another device or the cloud. Another QNAP FAQ goes further with the 3-2-1-1-0 rule: three copies, two media, one offsite, one offline (if cloud is used, it must be immutable), and zero errors (the backup must complete with zero errors). Note the distinction: 3-2-1 is common to both vendors, while 3-2-1-1-0 is the wording of that QNAP FAQ, not a term both vendors use. Synology also has a 3-2-1-1 variant: on top of 3-2-1, take immutable snapshots regularly as a last line of defence against advanced ransomware.

On tools, Synology uses Hyper Backup, with destinations including another Synology, a file server, an external hard drive or a public cloud, and settings for compression, scheduling, integrity-check scheduling and client-side encryption. If you have a second Synology, Snapshot Replication can copy data and settings to it, so that in a disaster the relevant tasks can be restarted directly on the replica unit. QNAP uses HBS 3, which brings backup, restore and sync together in one application and can back up to local, remote and cloud storage; source-side deduplication makes multi-version backups save space and bandwidth. HBS's first backup is a full backup, and later backups are incremental, sending only new or changed blocks. That last point comes from a QNAP community explanation, not an official document.

On immutable snapshots, Synology's knowledge base states that an immutable snapshot uses write-once, read-many technology, restricting any change or deletion during a set protection period; storage space containing an immutable snapshot (shared folder, LUN, namespace, storage pool) cannot itself be deleted. In other words, ordinary deletion is blocked, but destructive formatting or physical damage is not. The official recommended protection period is 7 to 14 days. The limits go with it: during the protection period, do not expect to delete it at will, and immutability only prevents snapshot deletion — it does not prevent the whole storage pool being formatted or physically damaged. Otherwise readers would wrongly believe that turning it on makes them invincible.

On backup verification, a backup without a restore test is unverified. First, a Hyper Backup task can run integrity checks manually or on a schedule, verifying backup data integrity and reporting errors; a third-party tutorial suggests doing this weekly and stresses that too many people back up but never verify, only discovering the problem when disaster strikes. That weekly frequency is a third-party tutorial suggestion, not an official mandatory frequency. Second, restore testing: after the first backup finishes, do not treat it as success straight away; actually restore a few files or one folder to a different location, without overwriting the original, and confirm the files open and the contents are correct. The third-party tutorial's point is: if you have never verified that a restore works, you do not really have a backup. Third, record three things: the backup task success notification, the integrity-check result, and the restore test date and which files were restored. For a small office, this article suggests one sample restore test per month; that frequency is this article's suggestion, not an official rule. Fourth, keep encryption passwords and keys somewhere else. Hyper Backup client-side encryption requires you to keep the password yourself, and the official knowledge base states plainly that the vendor cannot help you recover it, and losing it means permanent data loss. In other words, if the encrypted backup password is only stored on the NAS, or only in one person's head, losing it means losing the backup. Put the password in a second place, for example a password manager plus a paper copy kept outside the office, but never stick the password on the NAS itself.

On a cloud second copy, the advantages are offsite location, no need for a second unit, and no need to carry a hard drive away by hand. The disadvantages are that upload and download speeds are limited by broadband upload bandwidth, and cloud monthly fees plus later download or restore charges may apply. This research found no Hong Kong public quotation source, so this article states "no public source, please request an individual quotation" throughout, and does not copy US blog dollar estimates. The practical point is: use a separate, strong password plus two-factor authentication for the cloud backup account, and do not share the same credentials as the everyday NAS login, or a NAS compromise means the backup gets deleted too. That is a general security principle.

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6. Three remote-access routes: a trade-off between convenience and exposure

Further reading: Hong Kong Business Ransomware Response: First Steps, Ransom Risks and Backup Recovery

The source of vendor-relay convenience is clear: Synology's official positioning is remote access without setting up port forwarding or a fixed IP. A third-party comparison also notes that vendor relay wins on convenience and browser-instant access, while a private network wins on speed, coverage of non-Synology services, and the NAS itself not being findable on the public internet. Never present vendor relay as simply "unsafe" or "absolutely safe" — it is a trade-off between convenience and exposure.

For private-network installation on Synology, the official package is maintained by the service itself and can be installed directly from Package Center; after login, the NAS gets a private address, and a remote device installing the same client and logging into the same account can open the management interface with that address plus the system port. On QNAP, the service is in App Center, or the official package can be installed manually, with no UPnP or port forwarding needed, because the service establishes outbound connections and uses relay when necessary. Note that the private-network package on Synology or QNAP is not the same as that service's remote-login feature; remote NAS management is still through the web management interface.

Whichever route is used, the following official recommended settings apply. First, disable the default administrator account and open a separate administrator account. QNAP's official security document starts with exactly this: open a new administrator account, then disable the default admin account; and it specifies stronger passwords, two-step verification, regular checks for and removal of unknown accounts, tighter general user permissions, and installing only digitally signed apps. Another QNAP FAQ states plainly that disabling the default admin account has no adverse effect, and explains that a generic admin name leaves an attacker with only the password to guess. On Synology, third-party hardening guides and security checklists agree: disable the default admin, open a uniquely named administrator account, and enable automatic blocking — for example, blocking after three failures within 60 minutes, a figure that is that guide's example, not an official default value.

Second, two-factor authentication. Synology supports approve sign-in from a phone app, hardware security keys (including fingerprint and Windows Hello), and time-based one-time codes from authenticator apps; two-factor authentication can be forced for specific groups, and it integrates with automatic blocking and account protection, so failed verifications also count towards failed login attempts. Synology's official authentication page also lists automatic blocking, account protection and suspicious login notifications. QNAP's two-step verification requires a security code in addition to the account password at login. One reminder: before enabling two-factor authentication, record a backup email or backup codes, and do not delete the old authenticator app before changing phones, or you will lock yourself out.

Third, automatic blocking plus firewall plus not opening services you do not use. Synology lets you set how many failures, within how many minutes, and for how long to block; account protection sets a lockout threshold for untrusted clients; the firewall should allow only services or IP ranges that are needed. Third-party security checklists also suggest changing the default HTTP/HTTPS ports, forcing HTTPS plus installing a certificate, and disabling services you do not use (FTP, Telnet, SSH unless command-line access is really needed, SNMP, unused media server packages). QNAP's firewall can restrict the management ports to the local network or VPN only. Default management ports are 5000/5001 for Synology and 8080/443 for QNAP; if the ports have been changed, the changed ports apply.

The single most important sentence: do not expose the NAS management interface directly to the internet. As of 23 October 2026, the PHP2Shell vulnerability can be exploited before login; QNAP's 22 October 2026 advisory (advisory QSA-26-18, CVE-2026-109618 / CVE-2026-109619) lists several QTS, QuTS hero and QuTScloud versions as affected (affected versions include QTS 6.1.0, QTS 5.2.11 and earlier, QuTS hero h6.1.0 / h6.0.x / h5.2.11 and earlier, and QuTScloud c5.2.9 and earlier), with the status at the time being "fixing" and no fixed version available; Download Station and PHP Extensions will receive no fix because support ended on 30 September 2026, and QNAP advised backing up download tasks and then uninstalling them. QNAP's advice at the time was: turn off router port forwarding and UPnP, turn off automatic router configuration, unpublish services that are not needed, use a VPN for remote access instead, restrict management ports to the local network in the firewall, and turn off the built-in web server if it is not used. For Synology, reports at the same time said Synology had released updated PHP packages, but affected packages must be checked against individual advisories, and it must not be assumed that everything is fixed. The correct framing is: as of 23 October 2026, QNAP was still fixing the issue, and the official advice was to pull the NAS back into the local network plus VPN first; readers should check the vendor security advisory page for their own model and firmware version before buying or configuring.

On the risk assessment of the vendor cloud service itself, a third-party website security analysis notes that the domain itself has no malware, phishing or blacklist record, but NAS units using that service have a history of ransomware or remote attacks, commonly where firmware was outdated, the management interface was directly exposed, and UPnP or port forwarding was fully open. The safe posture is: keep the system updated, do not expose the management interface directly (use a VPN or local-network only), turn off UPnP and unneeded port forwarding, and use a strong, unique account password. When citing this, distinguish the domain itself from the configuration risk of the whole ecosystem, and do not simplify it to "the service is unsafe".

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7. Sharing with several people: use group permissions, not person-by-person clicking

The principle is simple: use group permissions, not person-by-person, folder-by-folder clicking. Synology's shared-folder wizard asks in turn for name, description, encryption and advanced settings (including recycle bin on/off, data checksum and folder quota), and then shows a permissions page; it is recommended to switch the permissions page from local users to local groups, giving the user group read-write permission, so that a new colleague only needs to join the group to gain access, and a departing colleague only needs to be removed from the group. QNAP lets you add users or user groups and set access rights in folder permissions, and advanced permissions allow subfolder permissions, setting read, read-write or deny layer by layer. QNAP's official document states the permission-conflict hierarchy: deny (no access) takes top priority, followed by read-write, then read-only; when a user's personal permission differs from the group permission, the effective permission must be calculated from this table. The most common failure point is assuming that group read-write means the individual has read-write, when a personal deny setting overrides everything.

A suggested folder structure for a small office (this article's suggestion, not an official rule): company shared folder, readable and writable by all staff (or readable by all, writable by a designated group); department or project folders, limited to the relevant groups; a personal home folder per person; a read-only reference folder for old quotations and contract templates, readable but not editable, so a wrong change is not a worry; and a backup-only folder, writable only by the backup account, which everyday users do not even need to see.

On quotas, Synology user quotas and shared-folder quotas are two different things. Shared-folder quotas (Btrfs) are set in the shared-folder settings, choosing the unit and filling in a number. User quotas are set in the user settings, and when group quotas and user quotas coexist, note which one takes effect first — the effective one is the user quota. Do not confuse the two, and test on your own model. QNAP quotas can be set in MB or GB for users and user groups; once enabled, a user who fills the quota can no longer write to the NAS, and the default is disabled. QNAP has three types: personal, group (a group quota applies to each user in the group individually, not as one shared total for the whole group), and all users; QuTS hero notes that quotas are counted per shared folder, not across folders, and a personal quota may override a group quota. Older documents describe quotas as counted per volume, not across volumes, so version differences depend on the QTS or QuTS hero version — check your own version's document before setting. Practical advice: on the first day, set a reasonable limit for personal home folders and shared folders (the number must be set from the company's actual usage; this article gives no universal number); when a quota is full, a file being saved will fail to write, so do not wait until it fills up — turn on storage-space notifications.

Versioning and the recycle bin are two safety nets against mistaken deletion. Synology enables the recycle bin by default when a shared folder is created; deleted files go to the recycle subfolder under that folder and can be restored from the file management interface, and the recycle bin can be restricted to administrators only. A third-party round-up gives default retention days, version counts and space share; those figures depend on the system version or settings, and your own NAS display is authoritative — they are not an official guarantee. QNAP's network recycle bin is also enabled per shared folder. One point to note: the recycle bin only rescues files deleted through a shared folder; it cannot rescue files deleted by other means (for example, deleted directly on the NAS itself, formatting, or storage-pool damage); and the recycle bin itself takes up space, so clean it regularly or it will keep growing.

On versioning, Synology Drive can set version control and rotation policy for team folders in the admin console; but note that the shared folder's own permissions take priority — if a user only has read-only rights to that folder, they cannot sync. In other words, versioning being on does not mean everyone is covered; it must be considered together with permissions. Snapshot versions and Drive versions must not be confused: a snapshot is a point in time for a whole folder, while a Drive version is the history of an individual file. Turning both on is the most reliable, but both take up space, so consider them together with quotas.

On sharing links, QNAP's document notes that if a user's read-write rights to a folder are revoked, sharing links they previously created for that folder also become invalid. Check a departing colleague's sharing links as well, and do not assume that removing them from a group automatically clears all links.

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8. UPS and power-cut protection: the signal cable is the key

For UPS connection, the USB signal cable is the key, not just plugging in the power. QNAP's official UPS document states that enabling UPS support protects the NAS from abnormal shutdown caused by a power cut; on power loss there are two options: shut down after a set time, or enter automatic protection mode after a set time (stopping all services and unmounting all volumes). No matter how many minutes are set, if the UPS remaining charge falls below 15%, the NAS will automatically shut down or enter automatic protection mode 30 seconds after the power cut, without waiting for the set time. For connection, USB standalone mode means connecting the UPS USB cable to the NAS, choosing shutdown or automatic protection, setting how many minutes to wait, and applying; SNMP standalone mode means the NAS and the SNMP UPS are on the same physical network, and the UPS IP is entered.

For Synology, the setting path is Control Panel, Hardware and Power, UPS; tick "Enable UPS support", and connect the UPS to the NAS USB port with a USB cable. You can set how long after a power cut to enter Safe Mode, and whether to send a shutdown signal to the UPS when entering Safe Mode; Safe Mode stops all services and unmounts volumes so the NAS can stop safely before the UPS runs out of power; if "restart automatically after power loss" is on, the NAS will power back on when power returns.

A common misunderstanding: a UPS is not "plug it in and it shuts down automatically". If only the NAS power is plugged into the UPS, with no USB or SNMP signal cable, the NAS has no idea the power is out, and will simply suffer a hard power cut when the UPS battery runs out — little different from having no UPS. Before buying a UPS, check whether that UPS model has USB or SNMP, and whether the NAS vendor's compatibility list includes it (readers should check the vendor website themselves; this article lists no model list, because lists change).

QNAP's manual describes power loss in three phases, which makes a good example for the article. Phase one runs from the power cut to the end of the waiting time: if the UPS charge is above 15%, shut down or enter automatic protection after the set wait; if below 15%, act automatically after 30 seconds; if power returns midway, the NAS keeps running normally. Phase two runs from the end of the waiting time until the UPS runs out of power: in automatic protection mode all services stop and shared folders and network drives become inaccessible; in shutdown mode it stays shut down. Phase three runs from the UPS running out until power returns: shutdown mode stays shut down, and after power returns it follows the power-recovery setting; automatic protection mode restarts on power return and restores its previous state. This phased explanation shows that automatic protection and shutdown are not the same thing: automatic protection is for getting back to work quickly after power returns, while shutdown is the most conservative choice.

On file systems, Btrfs has the design advantage of checksums for every data block and metadata block, verified on every read; metadata has two copies; when silent corruption is found, it can self-heal using another good copy of the data on a supported array (including RAID 1, 5, 6, 10, SHR); snapshots are point-in-time copies of a whole shared folder, and the copy-on-write structure means snapshots take only a small amount of extra space with little performance impact, with shared-folder snapshots possible as often as every 5 minutes (LUN snapshots every 15 minutes). Why copy-on-write matters for power cuts: a write does not directly overwrite the old block, but writes to a new block and only switches the pointer after confirming the write is complete; in other words, if power is lost halfway through a write, the old version remains intact, and there will be no half-old, half-new file.

But Btrfs also has limits, and it should not be treated as a cure-all. First, self-healing needs another good copy of the data — that is, redundancy. On a single-drive volume with no redundancy, checksums can only detect corruption, not necessarily repair it. Second, data that had not yet been written to disk at the moment of the power cut (for example, still in cache, not yet flushed) is still lost; Btrfs cannot conjure data that was never written. Third, a third-party comparison puts it directly: Btrfs suits home users who value data protection and snapshots, but it should be paired with a UPS plus a solid backup strategy; Ext4 wins on speed and maturity, but has no built-in snapshots. Choosing Btrfs is not about speed, but about snapshots plus checksums; if the workload is continuous large-file writes or surveillance recording, Ext4's speed advantage is worth considering — but file-system options depend on the model, and it must not be written as if every model lets you choose freely. Fourth, the first things to do after a power cut: power the NAS back on, check the system log or storage manager for anomalies, run a data scrub, and confirm that the latest snapshot and backup tasks are normal. That is this article's suggested procedure.

The correct way to test a UPS: during the day, when nobody is writing important files, watch the UPS status through the NAS interface, briefly unplug the UPS mains plug (not the NAS power cable), observe whether the NAS enters Safe Mode or automatic protection, then plug the mains back in and confirm the NAS returns to normal. Before testing, make sure backup is done and important files are saved. Things not to do: do not pull the NAS power cable directly to "see if it breaks"; do not run any power-cut test without a backup. This article gives no instructions for opening a UPS or replacing its internal parts; for such work, please use a qualified person, and do not touch high-voltage parts yourself.

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9. First-day checklist: do it in order, do not skip around

The pre-purchase decision checklist should be recorded alongside: write down the use case, since the use case decides the processor, memory, bay count and network port — do not let the bay count decide the use case backwards; calculate three-year capacity, current data plus annual growth, allowing for array overhead, and decide how many drives to start with and how many bays to leave free; check the model's official specification page for processor, memory limit, network ports, M.2 count, expansion-unit support and array support, and do not trust a retailer page's single line of "supports RAID 5" as applying to the whole line; check the drive compatibility list plus CMR, using the exact model number, and check the compatibility list again for M.2 drives used for a pool or cache; test the home or office upload speed (wired direct connection) and then judge whether remote-access expectations are realistic; and check whether the switch, network cards and cables in the whole chain are 2.5G.

The monthly or quarterly maintenance checklist after that: look at drive health reports, and replace a drive early on a degradation warning instead of waiting for it to fail; follow system updates; run restore tests regularly. For migrating from an old unit to a new one, Synology's migration tool requires the source system to be 6.0 or above and the destination to be 7.0 or above, the destination's original data and settings will be replaced by the source's, and the file system cannot be changed midway through migration; some settings are not migrated, including account settings, licences, some network settings, push service settings, desktop widgets and virtual machine manager settings; firewall and DHCP server settings are migrated but disabled by default. Before migrating, three things are essential: run a full backup plus a restore test on the old unit; check whether the old and new models and drives are on the vendor compatibility list; and record network settings, two-factor authentication backup methods and encryption passwords, and do not assume everything follows automatically. If a whole set of drives is moved across, the drives' bay order must follow the original unit — do not insert them at random. Cross-brand migration has no one-click settings transfer; only files can be restored from backup, with users, permissions and schedules reset by hand. Do not let readers think changing brands is a single click.

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10. Common misunderstandings, taken one by one

First, "an array is a backup" is wrong. An array only guards against drive failure, not deletion, encryption, fire, theft or the whole unit failing.

Second, "it works out of the box with no setup" is wrong. After unboxing, at minimum you must install the system, open an administrator account (not the default name), choose an update policy, create a storage pool and volume (choosing the array, and choosing Btrfs for snapshots and checksums), create shared folders and user permissions, turn on notifications, turn on a snapshot schedule, set up remote access (vendor relay or VPN, never exposing the NAS port directly to the internet), and turn on two-factor authentication. The file system must be chosen correctly from the start, because once a volume is created, its file system cannot be changed.

Third, "more bays are always better" is wrong. Bay count is only an upper limit, not a performance guarantee. Two bays are enough for mirrored backup plus file sharing, with the simplest management; four to six bays are worth buying for RAID 6, mixed media plus backup plus versioning. Buying too many bays but only fitting two drives means paying for the unit and the electricity for nothing; buying too few bays means replacing the unit when you later want RAID 6 or more drives. Processor, memory limit, network ports, M.2 count and software ecosystem often affect whether the unit is still usable in three years more than two extra empty bays do.

Fourth, "a 2.5G or 10G port means faster internet" is wrong. A fast local network does not mean faster internet upload. And "buying a NAS means having a backup" is also wrong. A NAS on its own is only centralised storage plus fault tolerance; without a second, independent copy, it is not a backup strategy.

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Frequently Asked Questions

Q1: Two bays or four bays?

If you only do backup, file sharing and photos, two bays plus mirroring is enough, with the simplest management. If data volume is expected to double within three years, or you want RAID 5 or 6, start with four bays or more, because two bays cannot add a third drive to convert to RAID 5 or 6. Calculate three-year capacity before buying, and do not jump straight to eight bays for a vague "maybe later".

Q2: Which drive should I buy?

For an array, buy a CMR NAS drive, for example Seagate IronWolf series, WD Red Plus or Red Pro, or Toshiba N300 series, checking the exact model number before buying. Plain WD Red is SMR and should not go into an array. Ordinary desktop drives are designed for a different purpose, and the risk is higher under continuous operation and multi-drive vibration.

Q3: Does turning on snapshots mean I have a backup?

No. Snapshots sit on the same unit; if the whole unit is gone or the storage pool is corrupted, the snapshots go with it. Snapshots rescue mistaken deletions and wrong changes; backups rescue whole-unit disasters. You need both, plus a restore test.

Q4: For opening NAS files from outside, which route is safest and most convenient?

No single route is both absolutely safest and most convenient — it is a trade-off. Vendor relay is most convenient for occasional photo viewing and document opening; a VPN is more solid for a small office with many people working remotely; a private network is the advanced choice for using all services without opening ports. Whichever route is used, disable the default administrator, enable two-factor authentication, enable automatic blocking and firewall, and never expose the management interface directly to the internet.

Q5: Is a UPS enough if it is just plugged into the power?

No. With power only, and no USB or SNMP signal cable, the NAS has no idea the power is out, and when the battery runs out the result is still a hard power cut. The signal cable must be connected, automatic safe shutdown or automatic protection must be set, and the setup must be tested once using the method in this article.

Q6: What are the Hong Kong authorised prices? What is the cloud backup monthly fee?

This research found no Hong Kong authorised public quotation source. NAS unit prices, drive prices, UPS prices and cloud storage monthly fees are all stated as "no public source, please request an individual quotation". US market reference prices cannot be treated as Hong Kong prices; please ask the supplier for an individual quotation before buying.

Q7: When migrating from an old unit to a new one, do the settings follow automatically?

Same-brand migration tools are limited; some settings are not migrated, including account settings, licences and some network settings, and the file system cannot be changed midway. Cross-brand migration has even less — no one-click settings transfer — only file restore plus manual resetting. Before migrating, always run a full backup plus a restore test, and record network settings, two-factor authentication backup methods and encryption passwords.

Q8: Does a faster 2.5G / 10G local network mean faster internet?

No. Local-network speed is limited by the slowest link in the chain; the speed of downloading files remotely is still capped by the home broadband upload limit. Even with 2.5G or 10G at home, downloads from outside will not exceed the home broadband upload ceiling.

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Series positioning

This article is a pre-purchase decision and first-day checklist guide. For the basics of choosing a NAS, RAID and 3-2-1 backup, see our introductory guide Home / Small-Office NAS: How to Choose, Configure RAID and Back Up with 3-2-1.

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Sources

• Synology official comparison: DS1525+ / DS425+ / DS925+
• Synology official comparison: DS725+ / DS925+ / DS1525+
• Synology official comparison: DS224+ / DS225+ / DS425+ / DS725+
• Synology DS1525+ review round-up
• DS425+ detailed specifications
• DS425+ review
• DS225+ entry positioning
• DS225+ memory source conflict table
• Cheaper Synology line four-model comparison
• Cheaper line versus Plus memory differences
• Cheaper line four-model overview
• QNAP 2026 buyer's guide
• QNAP short-depth rackmount introduction
• QNAP shown new models
• UGREEN new line specifications
• UGREEN 4-bay new line review specifications
• UGREEN autumn promotion price round-up (US promotion prices; no Hong Kong public source)
• UGREEN high-end and 4-bay key points
• UGREEN 4-bay dual 2.5GbE aggregation to 5G
• Asustor new line full specifications
• Asustor 2-bay new model detailed specifications
• Asustor new line US price round-up
• Asustor 2-bay new model review
• Asustor entry line specifications
• NAS drives versus desktop drives
• Server / NAS drives versus desktop drives
• CMR versus SMR guide
• WD Red / Red Plus / Red Pro distinction
• SMR rewrite principle
• SMR rebuild risk
• CMR / SMR examples by vendor
• Synology compatibility-list policy details
• DSM 7.3 relaxation scope
• DSM 7.3 restores third-party drive support
• Synology official RAID type table
• RAID conversion rules
• SHR mixed-capacity example
• SHR adding / replacing drives
• Ookla Hong Kong connectivity report, first half 2026
• NETVIGATOR multi-use service specifications
• Hong Kong Broadband speed guarantee test requirements
• 2.5G / 5G / 10G cable comparison
• 2.5G on Cat5e, new cables as Cat6
• 2.5G upgrade guide
• Upgrading to 2.5GbE without rewiring
• Slowest link, wired first
• Array setup and backup guide
• Five beginner NAS mistakes
• RAID is not a backup, 3-2-1 rule
• Synology first-time setup guide
• Synology storage pool and remote setup steps
• Synology setup guide: administrator account, update policy, remote service
• NAS buying guide: media, backup, arrays, security
• Classify before backup, external backup before array change, quarterly restore test
• Synology backup and disaster recovery strategy page
• Synology Hyper Backup to a remote unit knowledge base
• QNAP storage and snapshots quick start guide
• Synology immutable snapshot knowledge base
• Synology Snapshot Replication specifications
• Synology Btrfs official page
• Synology Hyper Backup tutorial: restore testing
• Hyper Backup tutorial: integrity checks
• QNAP FAQ: 3-2-1-1-0 rule
• Synology security guide
• Synology Secure SignIn specifications
• Synology authentication feature page
• QNAP security document: disabling default admin, two-step verification
• QNAP FAQ: effect of disabling the default admin account
• Vendor cloud service security analysis
• PHP2Shell, QNAP advisory, fixing status
• PHP vulnerability effect on NAS, Synology PHP package update
• Synology private-network installation tutorial
• QNAP private-network remote connection discussion
• Synology remote-access comparison
• Synology user management: group permissions
• Synology quotas
• QNAP shared folder and permission FAQ
• QNAP QuTS hero quota document
• QNAP permission-conflict hierarchy document
• Synology recycle bin enabling and restore
• Synology Drive tutorial: team folder versioning
• QNAP UPS document
• Synology smart UPS connection tutorial
• Btrfs copy-on-write principle
• Btrfs backup and restore practice
• UGREEN Ext4 versus Btrfs comparison
• Synology migration tool specifications

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Related articles

• Home / Small-Office NAS: How to Choose, Configure RAID and Back Up with 3-2-1

• Hong Kong Backup Strategy Guide: The 3-2-1 Rule Done Properly — Time Machine, Windows, Cloud and Offline Drives

• Hong Kong SME RAID Recovery: What to Do When It Fails